Correct me if I'm wrong, but Brittish Cycling does not equal UKAD as far as I understand.
So the argument should be "We don't believe UKAD will do anything with a positive of a Sky cyclist". Because if UKAD would publish a positive, certainly Brittish Cycling will act... not because they are pure and worthy... but because they probably have little choice.
This seems a bit risky though... somehow you would think there would be some integer persons at UKAD and if that leaks.... well suffice to say heads would roll. It's definitely not unheard of(see Lancegate), but it's a different ballgame nowadays with more pressure from the outside and a UCI that has changed directors.
If I were "evil" DB I would simply not take such a risk and try it the good ole fashioned way (hide/microdose/bribe 1-2 key people so you hget early warning). Seems a tad more controlable than counting on the good will of whole UKAD. But as I said, it happened before, so it's not as ridiculous as it should be
Is the antidoping authority the Cycling Union or a separate entity? or does that differ per every country?
If that's bothering you:
Riding up a huge mountain a few 1000 times is still making my head burst. It's absolutely squarely against any acceptable modern training method. The attrition on your muscles would be offsetting any potential gain (and there would be little of that to begin with). It's so far out there that either it's complete nonsense or they indeed used every pharmaceutical helper to recover. And even then it would be an idiotic (archaic!)training method.